Pilot fuel injector



Sept. 5, 1950 G. s. KAMMER PILOT FUEL INJECTOR Filed July 10, 1945 2Sheets-Sheet 1 2 Sheets-Sheet 2 Sept. 5, 1950 G. s. KAMMER PILOT FUELINJECTOR Filed July 10, 1945 FL //M space I2 is in communication throughthe ducts I5 and I8 with the fuel supply and is thereby maintained fullof fuel. After the plunger 2 has descended a short distance it coversthe ports I6, I6 and so cuts off this communication. Pressure in thespace I2 immediately rises and is exerted through the space around theupper part of the valve 25, 29, 30, the groove 32, the duct 26 and thecorresponding nozzle orifice 39 above the valve face 31. The valve isthereby opened against the effect of the spring 38, and injectioncommences.

At the same time a certain proportion of the fuel will leak through thecontrol orifice I9 and duct 20 backto duct I5 and the supply. The amountof fuel thus by-passed governs the amount of fuel which is discharged,through nozzle orifice 39, into the engine combustion space, that is, itgoverns the rate of pilot fuel discharge as well as the pressure in thepumping space.

At a certain point in the descent of the plunger 2 its lower edge coversthe control port I9, but at the same time the lower edge of the groove 8uncovers the port II]. The leakage through the control port I9 and duct20 ceases, and all the fuel displaced by the plunger is delivered to thecombustion space, a part of it as before through the groove 32, the duct26 and one of the nozzle orifices 39, but the major part of it throughthe port I9, the duct 2I, the groove 36, the duct 35, the groove 34, theholes 33, 33, the grooves 21, 27 and the remainder of the nozzleorifices 39.

Thus an additional quantity of fuel, equivalent to the entiredisplacement of the pump plunger can now find its way into the enginecombustion space, at the main rate of fuel discharge determined by thearea of the plunger and the rate of lift of the pump operating cam. Thisquantity, obviously, is substantially greater than the initial rate, orpilot rate of discharge.

The plunger continues its stroke downwards to the full amount determinedby the operating mechanism, but before the stroke is quite completed,the helical edge 9 uncovers one of the ports I6, whereby pressure in thespace I2 is relieved, the remainder of the stroke merely serving to pushfuel back to the supply. The spring 38 closes the valve 24, 31, sincethere is no pressure available to keep it open, and injection ceasesabruptly. The duration of injection is determined by the time elapsingbetween the uncovering of the ports I0 and I6, and this again isdetermined by the position of the helical edge 9 due to rotation of theplunger 2 by means of the rack I. The drawings show the plunger set forfull load or maximum injection.

It will be seen that the arrangement disclosed provides pilot injectionat a reduced rate and main injection at a substantially higher rate. Therate of fuel discharge at any instant depends on the cross-sectionalareas of the discharge orifices conveying fuel to the combustion spaceand of the leakage path returning fuel to the supply, the rate of liftof the operating cam and the area of the pump plunger, but it isindependent of the engine speed, which only governs :the injectionpressure.

There is no interval between pilot and bulk injection as in some knownforms of injector, the valve remaining open continuously from thecommencement of pilot injection to the conclusion of bulk injection.

Where reference is made above to times and rates, these must of coursebe understood in terms of crank angle, as is usual in internalcombustion engine practice.

What I claim is:

1. A fuel injection nozzle for an internal combustion engine whichincludes a valve seating, a valve member having a face to cooperate withthe seating, a stem joined to the valve member with longitudinal surfacegrooves therein, a sleeve tightly fitting and fixed to the stem toconstitute the grooves into fuel ducts, holes through the sleevecommunicating with the ducts near the said face of the valve member toconstitute nozzle orifices, a surface on the valve member exposed tofuel pressure exerted in a direction to move the valve member in thedirection of flow of the fuel in the ducts and thereby to open thevalve, and resilient means opposing the said movement to keep the valvenormally closed, said valve face being located adjacent said sleeveholes whereby the fuel finally leaves the nozzle orifices between thevalve seating and the face on the valve member and substantially clearof said seating and face.

2. A fuel injection nozzle for an internal combustion engine, saidnozzle including fuel supply ducts communicating with two differentdischarge ports of a fuel pump, a valve seating, a valve member having aface to cooperate with the seating, a stem joined to the valve memberwith longitudinal surface grooves therein, a sleeve tightly fitting thestem to constitute the grooves into fuel ducts, holes through the sleevecommunicating with the ducts near the said face of the valve member toconstitute nozzle orifices, communication means between some of the saidducts and one discharge port of the fuel pump, at least one other of thesaid grooves being longer than the remainder, communication meansbetween said longer duct and the other discharge port of the fuel pump,a surface on the valve member exposed to fuel pressure from either groupof ducts, whereby the valve member is moved by the fuel pressure in thedirection of flow of the fuel in the ducts, and resilient means opposingthe said movement to keep the valve normally closed, the valve being solocated that the fuel finally leaves the nozzle orifices between thevalve seating and the face on the valve member.

GEORGE STEPHEN KAMMER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

